The present invention is directed to a method for monitoring virtual connections within a digital telecommunication network that is formed of switching centers operating in asynchronous transfer mode (ATM) Via which information transmitted in synchronous transfer mode (STM) can also be switched.
In such a method, a monitoring cell which may potentially contain a sequence identifier, a particular about the length of an information cell block, but is sure to contain an error-detecting code word, is respectively allocated to the information cell blocks (having a cell header and an information part) to be transmitted, being allocated thereto at the point of origin of the transmission link carrying the virtual connection. An information falsification is then respectively recognized at the end point of the appertaining transmission link by renewed formation of an error-detecting code word and by comparison thereof to the error-detecting code word transmitted from the point of origin, whereby at least an alarm occurs at the point of origin of the appertaining transmission link in case of error.
The faulty insertion of information cells into the information stream, the loss of such information cells as well as the falsification of information cell blocks during the course of transmission on the transmission links can be recognized in this way.